In order to solve the problems of segregation defects in ZL205A alloy castings and clarify the influence of vibration on segregation structure and hardness, the electromagnetic vibration table was adopted as the vibration source to study the effects of vibration frequency, amplitude and time on segregation structure proportion and hardness of the alloy. The results show that the proportion of segregation structures decreases first and then increases, and the hardness increases first and then decreases with the increase of vibration frequency from 25 Hz to 55 Hz. When the vibration amplitude increases from 1 mm to 4 mm, the proportion of segregation structures decreases gradually and tends to be stable, and the hardness decreases first and then increases. With the increase of vibration time from 30 s to 75 s, the proportion of segregation structures increases and finally tends to be stable, and the hardness decreases first and then increases. Therefore, the vibration frequency has the most significant effect on segregation structure and hardness of the alloy, followed by time and amplitude. In addition, the precipitation of segregation structures also affects the hardness of the alloy. The results provide a theoretical reference for studying the change rule of solidification structure of ZL205Aalloy under vibration condition and for improving casting quality.